The present invention relates generally to diagnoses and therapeutics for cancer. Generally, the invention relates to methods of screening for cancer, methods of screening for agents to treat cancer and methods for treating cancer.
The cell cycle is a highly regulated event with each cycle comprising G1 phase for cell preparation before DNA replication, S phase for DNA replication, G2 phase for cell growth and preparation for division, and M phase for mitosis (nuclear division) and cytokinesis (cell division) to complete the cycle. In a normal cell, the S-M phases, separated by the preparative G1 and G2 phases, are tightly coupled so that only one round of S phase precedes each mitosis and mitosis is not initiated until one round of DNA replication is completed. As a result, chromosomal DNA is replicated precisely once per cell cycle. Failure of this S-M coupling results in aneuploidy (gain or loss of DNA) leading to abnormality in cell growth and function.
Centrosomes are the primary components of the microtubule organizing center in mammalian cells. The regulation of centrosome duplication in mammalian cells is tightly controlled in order to maintain genomic integrity and prevent aneuploidy. Hinchcliffe and Sluder, Gene Dev. 15:1167-1181 (2001). In addition to directing formation of the mitotic spindle, recent evidence indicates that the centrosome participates in cell cycle regulation. Hinchcliffe et al., Science 291:1547-1550 (2001); Khodjakov and Rieder, J. Cell Biol. 153:237-242 (2001). Cancer cells frequently contain elevated numbers of centrosomes (Lingle et al., Proc. Natl. Acad. Sci. U.S.A. 99:1978-1983 (2002); Pihan et al., Cancer Res. 58:3974-3985 (1998)), although whether centrosome amplification contributes to transformation or is a consequence of cancer progression has not been determined. Because centrosomes usually nucleate microtubules, cells with supernumerary centrosomes form multopolar mitotic spindles and may undergo mitotic catastrophe. (Margottin-Goguet et al., Dev. Cell 4:813-826 (2003).
Mitotic catastrophe is loosely defined as a form of cell death that occurs during mitosis and arises from aberrant G2 checkpoint control. Although the molecular details of mitotic catastrophe remain to be defined, several genes involved in the G2 checkpoint induce mitotic castrophe when disrupted, including 14-3-3 σ (Chan et al., Nature 401:616-620 (1999)), ATR (Brown and Baltimore, Gene Dev. 14:397-402 (2000)), and the CHK1 kinase (Takai et al., Genes Dev. 14:1439-1447 (2000)). In addition, defects in proteins required for the mitotic spindle assembly also induce catastrophe. Depletion of hNuf2, a kinetochore protein involved in microtubule attachment, arrests cells in prometaphase and induces mitotic cell death. (DeLuca et al., J. Cell Biol. 159:549-555 (2002). Because mitotic catastrophe is induced in proliferating cells, and also occurs following DNA damage in cells with mutations in checkpoint proteins, induction of catastrophe presents a promising opportunity for specifically targeting cancer cells.
The forkhead box (Fox) family of transcription factors plays important roles in regulating cellular proliferation, differentiation, longevity, and cellular transformation. Wang et al., Proc. Natl. Acad. Sci. USA 98:11468-11473 (2001). FOXM1, previously known as HFH-11, Trident, WIN and FKL16, is a Fox transcription factor widely expressed in proliferating cells.
It is suggested that FOXM1 is required for normal S-M phase coupling during cell cycle progression. FOXM1 levels increase at the start of DNA replication and persist until the end of mitosis in cells synchronized by serum starvation. Korver et al., Nucleic Acids Res., 25:1715-1719 (1997). FOXM1 knockout mice exhibit cell division defects including DNA polyploidy in the heart and the liver cells, indicating that expression of FOXM1 is required to prevent multiple rounds of S phase in one cell cycle. Korver et al., Curr. Biol., 8:1327-1330 (1998). Studies of cultured cells demonstrate that over-expression of FOXM1 alters cell cycle kinetics by facilitating progression through G2/M. Leung et al., FEBS Letters, 507:59-66 (2001). Moreover, it has been reported that FOXM1 protein and RNA levels were markedly increased throughout the period of lung repair when cells were undergoing extensive proliferation in response to acute lung injury. Kalinichenko et al., Am. J. Physiol. Lung Cell Mol. Physiol., 280:L695-L704 (2001). premature expression of FOXM1 in transgenic mice accelerates hepatocyte DNA replication and the expression of cell cycle regulatory proteins following partial hepatectomy. Ye et al., Mol. Cell Biol. 19:8570-8580 (1999). Elevated expression of FOXM1 has been reported in both hepatocellular carcinoma (Okabe et al., Cancer Res. 61:2129-2137 (2001)) and in basal cell carcinoma (Teh et al., Cancer Res. 62:4773-4780 (2002)). However, whether FOXM1 is essential for cancer cell proliferation has not been determined.
As a transcription factor, FOXM1 may exert its cell cycle regulation function by regulating the expression of other genes. It has been reported that FOXM1 activates the expression of cyclin B1 promoter but not of cyclin D1. Leung et al., FEBS Letters, 507:59-66 (2001). Additionally, studies using transgenic mouse models identified genes that are induced in regenerating livers of FOXM1 transgenic mice relative to wild-type control mice. These genes include several immediate early transcription factors (ID-3, Stat3, Nur77), MMP-9, and several stress response genes. Wang, et al., Gene Expr., 11: 149-62 (2003).
On the other hand, FOXM1 is a downstream target of glioma transcription factor-1 (Gli1) in certain cell carcinomas. Teh et al., Cancer Res., 62:4773-4780 (2002). Activation of Sonic Hedgehog (Shh) signaling plays a key role in the development of basal cell carcinomas (BCCs) of the skin in humans. It is reported that FOXM1 levels increase in BCCs and that expression of the Shh target Gli1 caused a significant elevation of FOXM1 mRNA level and transcriptional activation.
Specific gene targeting sheds light on the biological mechanism applied by FOXM1 in cell cycle regulation. In addition, such gene or protein targets may provide new candidates for therapeutics or diagnostics for cell proliferative disorders.
Cancer is a general term for a group of diseases that involve the growth and spreading of abnormal cells in the body. This disease develops when cells continue to grow and divide until they spread to other parts of the body, leading to tumor development and destruction or invasion of normal body tissue. Tumors ultimately form colonies of cells in certain parts of the body. Lung, colon, and breast cancers are among the most common cancer types. Other cancers include ovarian cancer, kidney cancer, skin cancer, Kaposi's sarcoma, esophageal cancer, stomach cancer, leukemia, and lymphoma.
Lung cancer causes more cancer-related deaths than breast cancer, prostate cancer, and colon cancer combined. The American Cancer Society estimates that over 170,000 new cases of lung cancer would be reported by the end of 2003. Lung cancer often begins in the bronchi, but it can appear in any of the parts of the lung. Once the cancer takes root it can spread to the other parts of the body through metastasis. Lung cancer is divided into two major types: small cell and non-small cell. Small cell lung cancer has small cells, but they can spread rapidly throughout the body affecting lymph nodes and other organs such as the brain, the liver and the bones. On the other hand, non-small scale lung cancer makes up nearly 80% of the diagnosis for lung cancer.
Colon cancer is an abnormal growth of cells in the digestive system. It is often called colorectal cancer because it can affect both the colon and the rectum. Colon cancer begins in the layers of tissue found in one of the four sections of the colon and develops slowly over time. It is usually first discovered as a polyp, or a small growth of tissue in the colon. According to American Cancer Society statistics, colon cancer is the third most common type of cancer among men and women. This type of cancer was estimated to affect 105,000 people by the end of 2003.
Breast cancer is a tumor that is originally found in the cells of the breast. It is most common in women, but can also be found in men as well. It is the most common form of cancer among women, other than skin cancer. Every year more than 200,000 women are diagnosed with the disease in the United States alone. It was estimated that, in 2003, nearly 40,000 American women would die of this disease. Women who have been diagnosed with breast cancer have a number of treatment options depending on the stage of the cancer. One of the most important factors about breast cancer is the concept of early detection.
As demonstrated above, cancer is one of the most pervasive diseases in the world today. However, definitive cures have not been established. As a result, innovative methods for treatment are constantly pursued. Indeed, one of the most important ways to control cancer is through early detection methods. The present invention addresses these needs.